Sofa



FIG. 1 is a front elevation view of a sofa showing the new design;

FIG. 2 is a back elevation view thereof;

FIG. 3 is a left-side view thereof;

FIG. 4 is a right-side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a perspective view thereof.

The broken lines indicate portions of the article that form no part of the claimed design. 

CLAIM The ornamental design for a sofa, as shown and described. 